dnscache.php

function loadIp($host){
        $filepath = "/dev/shm/ipcache";
        $ip = gethostbyname($host);
        $wfile = fopen($filepath, "w");
        fwrite($wfile, $ip);
        fclose($wfile);
        return $ip;
}

function getIp($host)
{
        /*Initialize variables*/
        $result = 0;
        $cltime = 0;
        $ttl = 3600;
        $filepath = "/dev/shm/ipcache";

        $shieldsquare_config_data   = new shieldsquare_config();
        $ttl = $shieldsquare_config_data->_domain_ttl;

        /*file doesn exist at all*/
        if(!file_exists($filepath))
        {
                echo "<p>Loading because file doesnt exist..<p>";
                $ip = loadIp($host);
        }
        /*file exists*/
        else
        {
                $rfile = fopen($filepath, "r");
                $result = fread($rfile,filesize($filepath));
                fclose($rfile);
                $cltime = filemtime($filepath);
                /*file exists with o content*/
                if(!$result || !$cltime)
                {
                        echo "<p>Loading to cache because file is empty..<p>";
                        $ip = loadIp($host);
                }
                else
                {
                        $life=time()-$cltime;
                        /*file exists with content but the value has expired*/
                        if($life>$ttl)
                        {
                                echo "<p>Loading the IP because the name record expired in the cache..</p>";
                                $ip = loadIp($host);
                        }
                        /*value has not expired*/
                        else
                                echo "<p>Using cached IP</p>";
                        $ip=$result;
                }
        }
        return $ip;
}